right now, assad still dominates the syrian government. he knows that using chemical weapons is going to trigger american-- could trigger american intervention. he does not want to do it now. he does not want american intervention. but if he's driven out of damascus and up against the wall in the west of syria and looks like he's going to fail, he might very well use them, especially if he thinks it would trigger american involvement because america could be his last line of defense and last protection against something much worse. >> i haven't seen any hard evidence that they've been used. there have been some reports, and if they were used it seems to have been on an extremely small scale. but again, i think there's no hard evidence. might they be used? sure, desperate leaders might do desperate things if they felt there was no alternative. i don't think there's anything we can do to prevent their use, other than to threaten, as we have, if they were to be used it would cross a-- quote, unquote-- red line and have dire consequences. the